1. Field of the Invention
The present invention relates to a tubular gripping mechanism. More particularly, the present invention the relates to a tubular gripping mechanism that can be used to grip different diameters of tubular. More particularly, the present invention relates to the diversion of a load associated with gripping a tubular. Additionally, the present invention the relates to a tubular gripping mechanism whereby the tubular is properly centered regardless of the diameter of the tubular.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
The term “tubular” as used herein includes all forms of drill tubulars, drill collars, pipe, casing, liners, bottom hole assemblies (BHA), and other types of tubulars known in the art. In well drilling and well completion operations, it is necessary to lift and properly align lengths of downhole tubulars. For example, in oil or water well drilling, multiple lengths of drill pipe must often be raised from a horizontal position at or near ground level to a vertical position aligned with the centerline of the well. Such lifting and aligning operations require clamps for securely holding the pipe in place as it is lifted. When a pivotally mounted pipe boom is used, this boom must support large loads in several different orientations.
Compounding this problem is the fact that each joint of a length of a down-hole tubular must be closely aligned with a string of such tubulars after it has been lifted to the vertical position, such as when a drill pipe or casing is made up. A clamp, or gripper, for this purpose should preferably provide a necessary alignment for down-hole tubulars having various diameters, without any adjustment. Proper alignment has been a problem with many such clamps, or grippers, of the prior art, especially those employing pivoted clamping jaws. When pivoted clamping jaws are used, there is a tendency for the center of the down-hole tubular to vary as a function of the diameter of the tubular being clamped.
U.S. patent application Ser. Nos. 11/923,451, filed on Oct. 24, 2007 and 12/013,979, filed on Jan. 14, 2008 by the present inventor, describe pipe handling apparatuses whereby pipe is moved from a horizontal position to a vertical position with a single degree of freedom. In particular, these devices include grippers that grasp the pipe when it is in a horizontal position, move the pipe through the interior of a frame through the use of a particular pipe handling structure, and then position the pipe directly over the well center. Through the use of this device, pipe is accurately moved without the need for adjustment actuators or other mechanisms in order to provide the proper end location for the pipe. Unfortunately, with this device, the grippers associated with the device must be changed, as necessary, so as to accommodate the particular diameter of the pipe being used. The formation of such separate grippers is somewhat difficult because the grippers must be able to properly center the pipe. As such, a need has developed to provide a pipe gripper assembly whereby various diameters of pipe can be accommodated with a single gripper assembly and whereby the pipes that are accommodated by this gripper assembly are properly centered therein.
In many circumstances, the pipe can have very rigid side walls. In other circumstances, such as installation of a casing, the side walls of the tubular are relatively thin and flexible. As such, there is a need to develop a pipe gripper assembly whereby the various thicknesses of side walls can be accommodated by the tubular gripping mechanism. It is important that the tubular gripping mechanism not bend, deform, puncture or otherwise dent thin-walled tubulars.
In the past, various patents have issued relating to a tubular gripping mechanism. U.S. Pat. No. 3,280,920 issued on Oct. 25, 1966 to P. Scott, teaches a portable apparatus for drilling down hole wells. This apparatus has a mast having an open side and a means for supporting a string of drill pipes rotated within the mast. A means for raising and lowering a string of drill pipes in a rectilinear direction parallel to the longitudinal centerline of the mast is provided. This apparatus includes a hydraulic cylinder connected through a suitable arrangement of lines and sheaves so as to apply positive force upon the power swivel so as to move the swivel upwardly or downwardly in the mast as desired. This swivel is mounted on a wheeled carriage which runs on suitable tracks carried by the mast. An elongate frame is pivotably attached to the lower end of the mast for swinging movement to an open side of the mast between a substantially horizontal position and an upright position. Releasable clamps are adapted to grip a section of drill pipe mounted on the frame for a limited longitudinal reciprocating motion thereon.
U.S. Pat. No. 3,365,762, issued on Jan. 30, 1968 to W. H. Spiri, shows a well pipe gripping structure having a slip body having a pipe gripping insert which is slidably movable horizontally into an arcuate guideway in the slip body. The slip body is retained within the guideway by upper and lower lips on the body. The lips have asymmetric retaining surfaces. The inserts are provided with teeth which advance vertically as the teeth advance circularly. The teeth of one insert are positioned out of alignment with the teeth of the other insert to increase the resistance to rotation of the pipe within the slip structure.
U.S. Pat. No. 3,561,811, issued on Feb. 9, 1971 to J. W. Turner, Jr., teaches a well drilling rig having a pipe racker apparatus in which a number of racker arms are controllable from a remote location to engage drill pipe tool joints and drill collars. One of the arms has a head for supporting the weight of lengths of pipe or drill collars being added to or removed from the drill string.
U.S. Pat. No. 3,702,640, issued on Nov. 14, 1972 to Cintrack et al., shows a tipping girder with a transfer of tubular elements. This tipping girder has a plurality of adjustable guide nippers movably positioned on the girder for movement transverse to the longitudinal axis thereof. There are adjustable locking nippers movably mounted on the girder for movement parallel to and transverse to the longitudinal axis thereof. The locking nippers are constructed to automatically engage and lock a rod on the girder when it is moved away from the horizontal position.
U.S. Pat. No. 3,806,021, issued on Apr. 23, 1974 to Moroz et al., shows a pipe centering apparatus. This apparatus has a carriage with a column mounted thereon to support a pipe end jointing mechanism. The carriage has a receptacle together with the column. The column pivotally supports a cantilever member of which the free extremity pivotably supports the pipe end jointing mechanism including coaxially arranged grippers adapted to retain the ends of the pipe.
U.S. Pat. No. 4,303,270, issued on Dec. 1, 1981 to H. L. Adair, shows a self-centering clamp for down-hole tubulars. This clamp includes first and second opposed clamping members guided along a clamping axis by first and second guide channels defined by a frame. Each clamping member defines a hydraulic cylinder in which is disposed a piston which is rigidly mounted to the frame. A rack is coupled to move with each of the clamping members. These racks are interconnected via a pinion gear which meshes with both racks so that the two clamping members move in a counter-directional manner and remain equidistant from a central point on the clamping axis.
U.S. Pat. No. 4,403,897, issued on Sep. 13, 1983 to Willis, provides self-centering clamp for drilling tubulars. This self-centering clamp includes first and second transverse guide rods. Two opposed clamping jaws are guided along the first guide rod. These jaws are positioned by two opposed rocker arms, each of which is mounted to a cross brace which slides along the second guide rod. The rocker arms are symmetrically positioned by a link mechanism which also slides along the second guide rod and by a hydraulic cylinder coupled between the two rocker arms. The frame is pivotably mounted to a pipe boom so as to rotate about an axis parallel to the clamped pipe and transverse to the first and second guide rods.
U.S. Pat. No. 4,650,237 issued on Mar. 17, 1987 to R. J. Lessway, provides an automatic centering and gripping apparatus which includes a housing in which is slidably mounted on a longitudinal movable operator body. A pair of gripper arms are slidably mounted on the operator body. Each gripper arm carries a gripper member engageable with a workpiece. The gripper members are moved longitudinally and laterally into gripping engagement with a workpiece when the operator body is moved in one longitudinal direction. They are correspondingly disengaged from the workpiece when the operator body is moved in the other longitudinal direction.
U.S. Pat. No. 5,609,226 issued on Mar. 11, 1997 to V. J. Penisson, teaches a slip-type gripping assembly having an outer body defining a longitudinal through opening for receipt of the object. A number of slip bodies are circumferentially spaced about the through opening and are radially movable toward and away from the locus of the object. Each slip body is pivotable about a generally longitudinal axis and generally circumferentially centered with respect to the slip body as well as about a tangential axis. A respective force transfer formation is cooperative between each slip body and the outer body for transferring radial force therebetween while permitting the pivoting.
U.S. Pat. No. 5,848,647, issued on Dec. 15, 1998 to Webre et al., shows a pipe gripping apparatus for angularly adapting two misaligned pipe on one or more pipe strings. The apparatus has a housing having internal, opposing downwardly-curved surfaces therein and forming a longitudinal opening for passing a portion of at least one tubing string therethrough. A plurality of slip carriers each has an exterior surface contoured to match the downwardly curved surface and has a downwardly inclined interior surface. Each slip carrier is in movable connection with one of the curved surfaces of the housing. A plurality of slips have downwardly inclined exterior surfaces and longitudinal channels formed on an internal surface for holding gripping elements for gripping a portion of the pipe
U.S. Pat. No. 5,992,801, issued on Nov. 30, 1999 to C. A. Tones, discloses a pipe gripping assembly and method. This pipe gripping assembly has primary pipe gripping mechanism and a backup and a secondary pipe gripping mechanism carried in a single tapered slip bowl. The primary gripping mechanism employs smooth surface pipe dies that set against and grip and hold the pipe without damaging the pipe surface. After the primary mechanism is set, toothed dies in the secondary gripping mechanism are automatically engaged with the pipe with only a minimal pipe gripping force. Additional slippage of the pipe through the smooth dies sets the toothed dies down against a wedging surface to grip and hold the pipe to stop its downward movement. A resilient biasing device is used to urge the toothed dies away from the pipe before the smooth dies are set.
U.S. Pat. No. 5,993,140, issued on Nov. 30, 1999 to A. Crippa, shows an apparatus for loading pipes onto processing machines. This apparatus has a handler arm with a first segment and a second segment disposed in succession. Kinematic members are adapted to determine a fixed ratio between the rotation angles of the segments about the respective hinging axes.
U.S. Pat. No. 6,543,551, issued Apr. 8, 2003 to Sparks et al., discloses an automatic pipe handling device which includes a support frame mounted on a boring device. Removable pipe racks can be placed in position on the support frame to deliver pipe to the spindle axis or to remove pipe therefrom as required. The pipe sections are removed from the pipe rack and positioned on the spindle axis by pipe grippers mounted on hydraulic cylinders mounted on a rotating longitudinal shaft. The grippers and shaft simultaneously return the used pipe sections for storage to the pipe rack.
U.S. Pat. No. 6,543,555, issued on Apr. 8, 2003 to M. Casagrande, provides an automatic loader for drill rods adapted to be used in association with a boring machine. The automatic motor has a store containing a plurality of drill rods and a movement assembly that is able to selectively remove, one at a time, the drill rods from the store to position them on the guide and drive assembly. The movement assembly is arranged in an intermediate position between the store and the guide and drive assembly so as to not interfere with the latter during the removal of the drill rods from the store.
U.S. Pat. No. 6,845,814, issued on Jan. 25, 2005 to Masson et al., teaches a pipe-gripping structure having load rings. In particular, a rotary slip supports a drill string having a plurality of slip segments connected to define an opening for insertion of the drill string. Each slip segment has a head region, a toe region, and an inner radial surface axially extending between the head and toe regions. The inner radial surface of each slip segment comprises a circumferential groove. A plurality of axially aligned drill string gripping inserts are attached to each slip segment between the head region and the circumferential groove. Each insert has a gripping surface for contacting the drill string.
U.S. Pat. No. 7,055,594, issued on Jun. 6, 2006 to Springett et al., describes a pipe gripper and top drive system in which the pipe gripping system is located beneath the top drive unit. The pipe gripping system has an open throat for receiving a tubular to be gripped by the pipe gripping system. The gripping system has a body with first and second jaws movably connected thereto and a piston/cylinder assembly movably interconnected with each jaw for moving the jaws to clamp and then to rotate the pipe.
U.S. Pat. No. 7,090,035, issued on Aug. 15, 2006 to G. Lesko, describes a method and system for connecting pipe to a top drive motor. This system includes a top drive motor that tilts about a horizontal axis and a pipe launcher that brings joints of pipe up to the drilling platform for connection with a top drive motor at a safe and convenient height above the platform. The top drive motor further includes a clamping assembly that grasps and pulls the joint of the pipe to the motor as the connection is being made. The clamp assembly supports the motor-pipe connection as the top-drive motor is raised in the drilling mast of the rig bringing the joint of pipe up into a vertical orientation for connection with the drill tubing string.
U.S. Pat. No. 7,121,166 B2, issued on Oct. 17, 2006 to Drzewiecki, discloses a tong assembly that has a body and a center member slidable relative to the body. A pair of clamping arms are rotatably connected to the body. The clamping arms are connected to the center member such that as the center member slides relative to said body, the clamping arms rotate relative to the body. The assembly also comprises a plurality of die assemblies, wherein at least one die assembly is mounted to each clamping arm and at least one die assembly is mounted to the center member.
U.S. patent application Ser. No. 12/111,907, filed on Apr. 29, 2008 by the present inventor, discloses a pipe gripping apparatus that has a first jaw with a pipe-contacting surface at one end thereof, a second jaw having a pipe-contacting surface at one end thereof, a tongue having a pipe-contacting surface at one end thereof, and an actuator connected to the first and second jaws and to the tongue. The actuator serves to move the first and second jaws and the tongue such that the pipe-contacting surfaces thereof move radially inwardly simultaneously for a substantially identical distance. A first link pivotally connects the tongue with the first jaw. A second link pivotally connects the tongue with the second jaw. The first and second links extend angularly outwardly from the tongue. The first and second pivot points of each jaw have a distance unequal to a distance between the first pivot point and pipe-contacting surface of each jaw. The pipe-contacting surfaces can be elastomeric pads, toothed dies, or rollers.
A problem associated with using the pipe gripping apparatus disclosed in U.S. patent application Ser. No. 12/111,907 is that a large load is imparted onto the outer surface of the pipe by the jaws of the apparatus. The large load is sustained by the actuator of the apparatus; however, the piston and cylinder of the actuator can prematurely fail due to constant application of the load of gripping to the pipe. Thus, there is a need for a gripping mechanism that reduces the load on the piston and cylinder of the actuator so as to increase the useful life thereof and avoid early fatigue and failure.
Various patents have issued relating the loads exerted by gripping mechanism. For example, U.S. Pat. No. 6,279,662, issued on Aug. 28, 2001 to Sonnier, discloses a conventional center-latch elevator with smooth slip segments of the present invention is employed to grip and suspend a pipe without damaging the pipe surface. The slip segments are made of aluminum or another material that is softer than the material of the pipe. The elimination of rough surfaces on the slip segments prevents damage to the external pipe surface. A threaded lift connector is secured to the box end of the pipe to be lifted. The lift connector forces spring-loaded slip segments down into the conical bowl of the elevator to move the segments radially inwardly into gripping engagement with the pipe. The axial forces exerted by the elevator against the bottom of the lift connector are transmitted through the connector to the threads engaged in the pipe.
U.S. Pat. No. 4,869,137, issued on Sep. 26, 1989 to Slator, discloses an improved jaw construction for power tongs and bucking units wherein the jaws include a pair of gripping pads which are mounted to the jaws with a resilient insert so that loads applied through the jaw to the pipe are distributed over the gripping pads to minimize scoring the pipe or deformation thereof.
It is an object of the present invention to remove the hydraulic cylinder of the actuator of a gripping mechanism from a load path.
It is another object of the present invention to increase the useful life of the actuator of a gripping mechanism.
It is another object of the present invention to lock the gripping mechanism around a tubular in the event of a loss of power to the gripping mechanism.
It is still another object of the present invention to use the gripping power of a gripping mechanism for other purposes, such as rotating tubulars, while the gripping mechanism holds a tubular.
It is another object of the present invention to provide a tubular gripping mechanism that can be used as a tong.
It is another object of the present invention to provide a tubular gripping mechanism whereby different diameters of tubular can be gripped by the same mechanism.
It is another object of the present invention to provide a tubular gripping mechanism which self-centers the tubulars regardless of the diameter of the tubular.
It is another object of the present invention to provide a tubular gripping mechanism which includes a locking mechanism so as to prevent unintended release of the tubular.
It is still another object of the present invention to provide a tubular gripping mechanism that can be used in conjunction with a tubular handling device.
It is another object of the present invention to provide a mechanism to grip and to center any shape having three surfaces with the same radius to the center of the shape.
It is another object of the present invention to provide a mechanism to grip and to center any shape having a means for variable locking of the shape.
It is still another object of the present invention to provide a mechanism to grip and to center any shape, clamping with a greater force than the actuator.
It is another object of the present invention to provide a mechanism to grip with zero centering error for any two tubular diameters.
It is another object of the present invention to use three points of contact for gripping a tubular.
It is another object of the present invention to have an infinitely variable brake position.
It is another object of the present invention to multiply the gripping force of the gripping mechanism so as to enhance the load delivered by the cylinder of the actuator.
It is another object of the present invention to lock the jaws of a gripping mechanism around a tubular.
It is still another object of the present invention to avoid elastic and plastic deformation of a tubular while gripping.
It is another object of the present invention to distribute the contact pressure of the gripper mechanism over the surface of the tubular.
It is another object of the present invention to provide a tubular gripping mechanism with a single actuator with a single degree of freedom.
It is another object of the present invention to move the tubular to the gripper.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.